Release paper-intelligence 0.5.1

[odfalik]

Patch release

The published 0.5.0 distribution metadata was correct, but runtime paper_intelligence.__version__ still reported the stale hardcoded value 0.2.0.

• update runtime version to 0.5.1
• configure Hatch to derive distribution metadata from _version.py, eliminating the duplicate version source
• add 0.5.1 changelog entry

Validation

• focused suite: 14 passed
• uv lock --check
• uv build: wheel and sdist built; wheel metadata reports 0.5.1
• git diff --check